14N Nuclear Quadrupole Resonance in Compounds Containing N–N Bonds. II. Hydrazides

¹⁴N nuclear quadrupole resonance studies at 77°K were performed in 14 hydrazides. The results indicate extensive delocalization of the charge in the pi orbital of the substituted nitrogen atom; the charge lost to the acyl oxygen is of the order of 0.30 electrons. This loss of pi electrons is partially balanced by an increased polarization of the sigma bonds. In symmetrical hydrazides this amounts to an excess charge density of order of 0.10 electrons. In hydrazides retaining an −NH₂ group, the charge in the $\mathrm{N–N}$ bond is polarized towards the substituted nitrogen atom amounting to 0.07 electrons transferred to the substituted nitrogen atom.